Tropical Storm SIX Advisory Mon Aug 10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (SIX)
WARNING NR 003//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 06W (SIX), LOCATED APPROXIMATELY 226 NM EAST-
SOUTHEAST OF CHICHI JIMA, HAS TRACKED WESTWARD AT 06 KNOTS OVER THE
PAST SIX HOURS. THE CURRENT POSITION IS SITUATED WITHIN AN EXPOSED
LOW-LEVEL CIRCULATION CENTER EVIDENT IN MULTISPECTRAL SATELLITE
IMAGERY. THE INTENSITY OF 40 KNOTS IS BASED ON A CONSENSUS OF
SUBJECTIVE DVORAK AND AUTOMATED INTENSITY ESTIMATES FROM MULTIPLE
REPORTING AGENCIES. A 092248Z METOP-A ASCAT PASS INDICATES WINDS
SPEEDS OF AT LEAST 30 TO 35 KNOT NEAR THE CENTER OF THE COMPACT
SYSTEM. TS 06W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF
A SUBTROPICAL STEERING RIDGE (STR) TO THE NORTH. THE SYSTEM IS
PASSING OVER WARM WATER (29-30C) IN AN AREA OF MODERATE TO STRONG
(20-25 KTS) VERTICAL WIND SHEAR (VWS). INCREASING EASTERLY VWS HAS
LEFT THE LOW-LEVEL CIRCULATION PARTIALLY EXPOSED, AND CONFINED THE
DEEPEST CONVECTION TO THE WESTERN PERIPHERY. HOWEVER, UPPER LEVEL
OUTFLOW TOWARD A NARROW TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) TO
THE WEST IS HELPING TO SUSTAIN THE SYSTEM IN THE PRESENCE OF THE
INCREASING VWS.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 06W WILL CONTINUE TRACKING WESTWARD ALONG THE SOUTHERN EDGE
OF THE STR. THE ENVIRONMENT WILL BECOME INCREASINGLY UNFAVORABLE AS
VERTICAL WIND SHEAR INDUCED BY STRONG EASTERLY FLOW ALOFT PERSISTS.
DESPITE THE PERSISTENT SHEAR, PASSAGE OVER WARM WATER AND A
FAVORABLE OUTFLOW PATTERN IN THE NEAR-TERM SHOULD ALLOW THE SYSTEM
TO REMAIN INTACT AS A WEAK TROPICAL STORM OR TROPICAL DEPRESSION
THROUGH TAU 72.
   C. TS 06W IS EXPECTED TO FINALLY SUCCUMB TO INCREASING VWS AND
DISSIPATE BY TAU 96. NUMERICAL MODEL SOLUTIONS REMAIN IN TIGHT
AGREEMENT, LENDING HIGH CONFIDENCE TO THE OVERALL JTWC FORECAST
TRACK.//
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